Method of making mineral wool mixture



.Oct. 3, 1933.

J. B. NEAL 1,928,699

METHOD OF MAKING MINERAL WOOL MIXTURE Original Filed July 27, 1927 Patented Oct. 3, 1933 UNITED STATES PATENT OFFICE James B. Neal, Lockport, N. Y., assigncr, by mesne assignments, to Johns-Manville Corporation, New York, N. York Y., a corporation of New Original application July 27, 1927, Serial No. 208,810. Divided and this application October 6, 1931. Serial No. 567,203

3 Claims.

This invention relates to the manufacture of heat insulating materials comprising mineral wool or rock wool filaments and sustaining or strengthening fibres, such as asbestos; one object 5 of the invention being the provision of a durable,

fire-resisting, heat insulating material, adapted to such uses as the insulation of ice-houses, cold storage rooms, steam pipes, etc.

The filaments of mineral wool are vitreous, and though to a sensible degree flexible and elastic, are nevertheless brittle and tend to break up into small fragments forming a coarse dust; this deterioration of the product is not only incident to handling but also occurs after it has been placed in wall-spaces for heat insulation purposes, as a result of jarring and vibrations to which all structures are subjected more or less.

By the invention herein described, sustaining or reinforcing fibres, inherently tougher than mineral wool filaments, are intermixed with the mineral wool filaments with substantially uniform distribution; the mixture is effected without subjecting the mineral wool to mechanical handling, and preferably before the mineral wool fibres or filaments have settled for the first time after their formation by the usual pneumatic means. Once the mineral wool filaments have settled on each other to form a loose, tangled aggregate, they can not thereafter be freely separated or dispersed as individual filaments and therefore no fully satisfactory approximation to a uniform distribution of other fibres through the aggregate is possible. This invention in its aspect of method and in its preferred mode is characterized by the introduction of dispersed sustaining fibres among the mineral wool fibres by pneumatic means, while both the mineral wool filaments and sustaining fibres are held suspend- .ed and dispersed in pneumatic currents, which by their intermixture and confluence cause mutual intermixture of the two kinds of fibre preferably before the mineral wool fibres have settled out of the streamof air and water vapor which bears them from their point of origin, where the molten slag or rock is blown into filaments by the steam jet in the well known manner. Other aspects and features of the invention will transpire from the description herein below.

The physical conditions which characterize this invention might measurably be obtained by imperfect dispersion of mineral wool fibres by pneumatic means applied thereto after their initial settlement and mixture therewith, while in such state of dispersion as might be thus effected, of dispersed sustaining fibres.

The material preferred, for imparting strength and durability to a fibrous mass predominantly consisting of mineral wool, is asbestos fibre, which is, like the mineral wool itself, incombustible.

The method will be explained by reference to the drawing hereto annexed, which represents an apparatus by which the method may be practiced and the product obtained. In this drawing, A represents a cupola furnace, in which the rock or slag material is fused, B the tap from which fused rock is drawn to flow in a thin stream, C the nozzle from which a steam blast issues, to disrupt the stream of melted rock and draw it out into fine filaments; D the wool-bin, D the aperture in the side of the wool-bin through which the gaseous stream, bearing dispersed rock filaments, is blown, K a conveyor on which the rock wool W settles and is conveyed out of the wool-bin through the aperture D therein.

The travel of the conveyor is adjusted so that the fibrous material is removed from the woolbin at the same rate that it is delivered in; this prevents accumulation of fibre in the bin and consequent reduction of the free air space therein, and thus preserves constant the conditions under which the two classes of fibres are mixed together, ensuring a uniform mixed product.

To accomplish this object with a minimum of fracture of the mineral wool fibres, pneumatic, as distinguished from mechanical means for producing a state of dispersion of the fibres, are em-' ployed, particularly with respect to the mineral wool fibres. The sustaining fibres, as of asbestos, being mechanically stronger than the mineral wool fibres, may, and normally will, be subjected to mechanical dispersion in preparation for interspersion with the mineral wool fibres.

Furthermore, as the mineral wool fibres are, as an incident to their mode of formation, initially home by and suspended in a state of dispersion in, a pneumatic stream, the object of mixture with sustaining fibres with a minimum of damage to the mineral wool fibres will best be served by effecting this mixture while the mineral wool fibres are in their initial stage of dispersion, and before their first settlement into a mass of tangled filaments.

Referring again to the drawing hereto annexed:

. P represents an air-pipe leading from an in take G to a fan-blower F. The intake G is preferably from the interior of the wool-bin D, so that floating fibres will be drawn to the blower and so that the introduction of the asbestosfibre bearing blast-will not lower the temperature or increase the pneumatic pressure in the wool-bin. L represents a feed box for introducing asbestosfibre to the intake pipe P. H represents an airblast pipe, leading from the blower E to the delivery-noihle 1, within the woolbin, which is so (1 ected as to deliver an air stream in which ashes fibres are dispersed and borne, into confluence with the pneumatic stream which bears dispersed mineral wool fibres W. The confluence of these two fibre-bearing streams produces eddies which effect a substantially uniform mutual intermixture of the two types of fibres, while the mineral wool fibres are, so to speak, in their nascent stage, so that, as the mixed fibres settle on the conveyor K in a mixture M, the mineral wool fibres are matted loosely for the first time, and settle with the dispersed asbestos fibre uniformly distributed through the mass. Thus the mixture of sustaining fibres with mineral wool fibres is effected with no more mechanical injury to individual mineral wool fibres than is incidental to the primary settling of the said fibres.

While, in the fibre-mixture thus produced small tufts of asbestos fibre will be perceptible, these are accounted for by the unavoidable imperfections in the dispersion of the asbestos fibres; a large proportion of the asbestos fibres is distributed as single fibres or very small aggregates, throughout the mass of mineral wool fibre.

The proportion of mineral wool to asbestos may be varied to suit the purposes of the manufacturer. The normal variations will lie, probably between 20% and 50% of asbestos, to and 50% mineral wool fibre.

The uniformity of distribution of sustaining fibres through a mass of mineral wool fibres, produced by the above-described method minimizes the liability of the matted fibres to be broken and crushed in handling and thus preserves the heat-insulating efllciency of the fibre mass. The adjusted rate of travel of the conveyor belt K contributes to this end, since the continuous removal of the fibre mixture from the wool-bin permits its accumulation into a deep mass and dispenses with intermittent mechanical removal or" such masses. Moreover, as the mixture of the two classes of fibres is efiected by pneumatic currents and eddies, it is important to maintain unchanged the volume and shape of the space within which such currents and eddies perform their function; this is provided for by the correspondence between the rates of introduction and withdrawal of fibre material.

I claim:

1. Method of making a mixture of mineral wool filaments and sustaining fibers, characterized by feeding fused rock into a fluid stream to form mineral filaments in fluid suspension and directing pneumatically suspended and dispersed supporting fibers between the suspended filaments, and then allowing the resulting mixture to settle.

2. Method of making a mixture of mineral wool filaments and sustaining fibers, characterized by blowing fused rock into the air to form dispersed mineral filaments, directing sustaining fibers upon a pneumatic stream into intermingled relation with the filaments while still in the air, and permitting the resulting mixture to settle.

3. Method of making a mixture of mineral woolfilaments and sustaining fibres, characterized by employing a fluid stream directed into the air to form filaments from fused rock, employing a confluent pneumatic stream to bear sustaining fibers so that the fibers are mixed with the mineral filaments while the latter are still in the air, and allowing the filaments and fibers to settle as thus mixed.

JAMES B. NEAL. 

